ICI 216140 is a GRP bombesin receptor 2 antagonist (IC50: 2 nM in vitro). At 2 mg kg, it can decrease bombesin-stimulated pancreatic amylase secretion in rats. At 1 mM, it has been proved to attenuate bombesin-stimulated increases in blood pressure in rat
Neuromedin C is a bombesin-like neuropeptide that stimulates uterine smooth muscle contraction and the release of gastrin , somatostatin, and amylase in rats. Neuromedin C is a truncated form of gastrin-releasing peptide corresponding to the GRP amino acids 18-27. It inhibits GRP and bombesin binding to rat pancreatic membranes (IC50s = 0.4 and 2.2 nM, respectively), which can be reduced by sodium chloride and guanylyl imidodiphosphate . Neuromedin C induces scratching and mast cell degranulation in mice when administered intradermally at doses ranging from 1 to 300 nmol site, which is inhibited by the BB2 bombesin receptor agonist RC-3095 and reduced in mast cell-deficient mice. Neuromedin C (3.2 nmol kg, i.p.) reduces rat glucose consumption by approximately 50% for up to one hour.
Gastrin-releasing peptide (GRP) is a neuropeptide that stimulates gastrin release. It binds to (Ki = 300 nM) and stimulates amylase secretion in rat pancreatic AR42J cells (EC50 = 0.3 nM). GRP increases proliferation of human liver carcinoma HepG2 and MHCC97H cells but does not affect the proliferation of normal HL-7702 liver cells at a concentration of 1 nM. In vivo, GRP (0.35 nmol/kg/h) increases both pancreatic exocrine secretion and pancreatic polypeptide (PP) release in rats. It dose-dependently stimulates gastrin, pancreatic amylase, lipase, bilirubin, and acid output and induces gallbladder contraction in humans when administered at doses ranging from 1 to 27 pmol/kg per hour.